The proteases are a very broad group of enzymes which carry out an enzymatic function of hydrolysing a peptide bond. Within the group, there is a wide range of substrate specificities for the amino acids adjacent the cleavage sites. Proteases are typically categorized on the basis of their catalytic mechanisms, e.g., based upon studies of their active sites, or by the effects of pH. Four main categories of proteases are serine proteinases, sulfhydryl proteases, acid proteases, and metalloproteases. They may also be classified according to their cleavage sites, e.g., endoproteases, amino peptidases, or carboxy peptidases.
Proteases have traditionally held a large share of the industrial enzyme market. Proteases are used in many industrial processes, including in detergents and cleaning products, e.g., to degrade protein materials such as blood and stains, in leather production, e.g., to remove hair, in baking, e.g., to break down glutens, in flavorings, e.g., soy sauce, in meat tenderizing, e.g., to break down collagen, in gelatin or food supplement production, in the textile industry, in waste treatment, and in the photographic industry. See, e.g., Gusek (1991) Inform 1:14-18; Zamost, et al. (1996) J. Industrial Microbiol. 8:71-82; James and Simpson (1996) CRC Critical Reviews in Food Science and Nutrition 36:437-463; Teichgraeber, et al. (1993) Trends in Food Science and Technology 4:145-149; Tjwan, et al. (1993) J. Dairy Research 60:269-286; Haard (1992) J. Aquatic Food Product Technology 1:17-35; van Dijk (1995) Laundry and Cleaning News 21:32-33; Nolte, et al. (1996) J. Textile Institute 87:212-226; Chikkodi, et al. (1995) Textile Res. J. 65:564-569; and Shih (1993) Poultry Science 72:1617-1620.
While there are many uses for proteases, there is always the need for a more active protease under various specific conditions. There is a need for new proteinases of differing properties, specificities, and activities.